Consequences of chronic Interferon-gamma expression on the host

我们正在利用慢性IFN-γ表达的小鼠模型来确定对宿主的生物学后果以及这种表型与人类疾病的相关性。我们已经使用生物信息学方法来确定干扰素-γ mRNA的3'非翻译部分的保守区域。据信，这些保守区域代表基因结构中的重要调控元件，因为除非mRNA的非编码区提供一些进化优势，否则没有通过进化进行保守的内在原因。基于该分析，我们靶向小鼠干扰素-γ 3'非翻译区的160-bp区域进行缺失，因为该区域富含AUUA序列，并且这些区域先前已被证明在细胞因子基因mRNA不稳定性的调节中是重要的。敲除（KO）小鼠已在C57 BL/6遗传背景上成功产生，并且我们的数据表明，与野生型小鼠相比，该小鼠在基础水平和刺激后产生显著更多的干扰素-γ。此外，淋巴结、脾脏和胸腺的结构被破坏，肝脏表现出慢性炎症的迹象。随着CD 4+和CD 8 + T细胞的增加，T细胞稳态被破坏，并且小鼠中的T reg细胞具有更有效的抑制活性。对抗原刺激也有增加的TH 1应答和减少的TH 2应答。B细胞群也发生了改变，基线抗体产生也发生了偏移。在胸腺中也观察到B细胞频率增加，因此表明IFN-γ可能改变B细胞运输。除了表型结果外，B细胞对抗原的应答也被破坏，因为观察到IgM和Ig 2a ab应答增加，而IgG 1应答减少。还观察到强的抗DNA和抗核抗原抗体应答，表明慢性IFN-γ表达可能在狼疮的发展中起作用。雌性小鼠还发生原发性胆汁性胆管炎，这是一种病因不明的疾病。这是第一个在性别偏见方面重现人类疾病的小鼠模型，因为90%的人类病例发生在女性身上。PBC的发生可以通过CD 4 + T细胞转移到受体RAG小鼠。此外，小鼠在运动后出现明显的心脏缺陷，并且在短暂的运动后，它们的血清中显示出高水平的乳酸。.此外，小鼠已被证明对黑色素瘤易感，这可能是现在已观察到的IL-27基因表达水平增加的结果。IFN-γ和IL-27水平直接相关，并且IL-27受体基因的消除导致小鼠自身免疫状态的改善。总之，我们的方法对阐明干扰素-γ的生物学中涉及的多种机制表明干扰素-γ基因表达改变宿主体内平衡的复杂性。因此，我们现在已经开发了一种小鼠模型，用于理解和阐明长期慢性IFN-γ基因表达的系统生物学效应，导致宿主中的慢性炎症。

We are utilizing a mouse model of chronic IFN-gamma expression to determine the biological consequences to the host and the relevance of this phenotype to human disease. We have used a bioinformatics approach to identify conserved regions of the 3' untranslated portion of the interferon-gamma mRNA. It is believed that these conserved regions represent important regulatory elements in the gene structure, as there would be no inherent reason for conservation through evolution unless the non-coding regions of the mRNA provided some evolutionary advantage. Based on this analysis, we targeted a 160-bp region of the murine interferon-gamma 3' untranslated region for deletion as this region is rich in AUUA sequences, and such regions have been previously shown to be important in the regulation of cytokine gene mRNA instability. The knockout (KO) mouse has been successfully created on the C57 BL/6 genetic background and our data indicates that this mouse produces significantly more interferon-gamma at a basal level and upon stimulation as compared to the wild-type mouse. Furthermore, the architecture of lymph nodes, spleen, and thymus is disrupted and the liver exhibits signs of chronic inflammation. T cell homeostasis has been disrupted as increased CD4+ and CD8+ T cells are present and the T reg cells in the mouse have more potent suppressor activity. There is also an increased TH1 response and a decreased TH2 response to antigenic stimulation. The B cell population is also altered and baseline antibody production is skewed. B cells are also observed in the thymus at increased frequency, thus indicating that IFN-gamma may alter B cell trafficking. In addition to the phenotypic consequences, the B cell response to antigen is also disrupted as increased IgM and Ig2a ab responses are seen with a decrease in the IgG1 response. Strong anti-DNA and anti-nuclear antigen antibody responses are also observed suggesting that chronic IFN-gamma expression may play a role in the development of lupus. The female mice also develop primary biliary cholangitis, a disease that has no known etiology. This is the first mouse model to recapitulate the human disease with respect to sex bias as 90% of the human cases are in women. The development of PBC can be transferred into recipient RAG mice by CD4+ T cells. Additionally the mice develop a heart defect that is apparent after exercise and they exhibit high levels of lactic acid in their serum following a brief period of exercise. . Furthermore the mice have proven to be susceptible to melanoma that may be a result of increased levels of IL-27 gene expression that has now been observed. IFN-gamma and IL-27 levels directly correlate and elimination of the IL-27 receptor gene results in improvement of the autoimmune status of the mice. In summary, our approach towards elucidating the multiple mechanisms involved in the biology of interferon-gamma demonstrates the complexity by which interferon-gamma gene expression alters host homeostasis. Thus, we now have developed a mouse model for understanding and elucidating the systems biology effects of long term chronic IFN-gamma gene expression, resulting in chronic inflammation in the host.